So called “house dust” is widely considered by experts to pose health hazards to persons with allergies, asthma, or respiratory disorders and diseases. House dust may contain dirt, textile fibers, pollen, hair, skin flakes, residue of chemical and household products, cat and dog dander, decaying organic matter, dust mites, bacteria, fungi, viruses, and a variety of other contaminants. Literally, pounds of house dust accumulate on vents and in ducts that comprise the ventilating systems of both residential and commercial buildings. This house dust is becoming increasingly more harmful as Americans spend a larger percentage of their waking hours indoors, often aggravating allergies of the inhabitants.
Modern heating/ventilating/air conditioning (HVAC) systems typically incorporate air filters either just prior to the circulation fan of the systems or in the return ductwork. However, most often these filters comprise fiberglass or similar media that are reasonably effective against large debris, but are often inadequate in removing fine particulate matter, such as dust, dander, etc., from the circulated air. Such filters may trap as little as twenty percent of the particulate matter circulating in a ventilation system, allowing the remaining dust and debris to circulate in the household or work place. A considerable after-market industry has flourished providing both active and passive electrostatic air filters. However, such filters only address those particles in the air that pass through them after being returned from the living space. The filter does not affect dust and debris that is already present in the ducts downstream of the HVAC unit that may be disturbed by airflow and carried into the living space. Additionally, it is not uncommon to encounter ductwork that has been improperly installed or maintained. These ducts frequently leak, allowing dust and debris from the duct surroundings to enter the ducts. Often this is a major contributor to duct contamination.
Prior to the invention of duct vacuuming systems, one method of addressing this problem was by sealing the dust and debris to the inner walls of the ducts by coating it with a layer of a water-based resin, known in the trade as “duct sealer” or “soot sealer”. This compound is commonly used in fire restoration of ventilating systems. After physically cleaning and sealing the outflow registers, a hole is cut in the duct of the ventilating system. An electric misting fogger is then mounted over the hole. The fogger is activated and the soot sealer is dispersed throughout the ventilating system. The soot sealer forms a coating over the inner walls of the entire duct system, encapsulating dust and other harmful impurities. Thus, the dust is not removed from the system, but rather the sealant forms a new interior duct surface with the dust trapped between the duct wall and the sealant surface. This method has several inherent limitations. However, the drawbacks to this system is its cost and the fact that the water based soot sealer, given the right humidity conditions, may dissolve, thereby freeing trapped dust and debris.
A more recent approach to the problem of debris in ventilation ducts has been to use a rotating brush at the end of a flexible vacuum hose that is fed into each duct from each register location. The hose is fed toward the outflow portion of the HVAC system to the limit of the hose length. Practically speaking, the hose is usually about 25 feet to 35 feet long. Additionally, the vacuum-generating units of these systems have been quite large and, while mobile, were of such a size and weight that they are impracticable to take into an attic. Yet, because of excessively long ductwork, it has sometimes been necessary to make multiple entries along the duct system in order to completely clean the ducts. It is sometimes impractical to properly clean the ducts of modern homes with high, two-story ceilings with this system. Most of the available hose would be used just to reach a register that is 15 to 18 feet above the floor. Extending the hose by using additional lengths was difficult because of the need to also extend the brush drive mechanism throughout the additional lengths of the hose. Additionally, these conventional systems, due to their general configurations, may make it difficult to position the duct cleaning machine close to the system being cleaned in order to maximize use of available hose.
Accordingly, what is needed in the art is an apparatus that offers a more flexible and mobile approach for cleaning HVAC ducts.